Novel cDNA clones were isolated from the SL12.4 murine T-lymphoma cell line by subtraction hybridization against a sister cell clone which lacks expression of these genes. This proposal focuses on the three most interesting clones which possess unexpected and striking characteristics. All three are novel in that they have no significant similarity with known genes or gene products. They are regulated during embryonic development, show tissue specific expression in adult animals, and can be induced in well defined in vitro systems. One of the novel genes has the hallmarks of an onco-fetal gene. Another is expressed only in the T-lymphoid lineage and the transcripts are strongly induced during T cell activation. The third is inducible in SL12.4 cells undergoing maturation and is highly expressed in ovarian tissues and human ovarian carcinoma cell lines. Regulation of gene expression. The regulation of each of the genes will be examined under inducing and non-inducing conditions, in related and unrelated lineages, and in somatic cell hybrids formed between expressing and non-expressing cells. Rates of transcription will be assessed. The 5' regulatory region of each gene will be isolated and tested for function in transient transfection assays. In vitro experiments to assess DNA-protein interactions in the control regions will be examined. Identification of the protein product. Studies are proposed to isolate and characterize the protein products. One of the genes predicts a protein with 4 putative transmembrane spanning domains and is likely to be localized on the cell surface. The other two likely to be intracellular proteins. Antibodies will be prepared against the predicted proteins to assess the physical properties of the protein, potential glycosylation, subunit structure and to determine the subcellular localization of each. Analysis of novel gene expression. The expression of the genes will be examined in AKR animals at discrete stages of lymphoma development using a model system developed by Dr. Esther Hays (who will provide the cells). Expression of the genes will be examined in selected adult tissue and during embryogenesis using in situ hybridization.